Documents EP 1 271 588-A1 and EP 1 271 589-A1 disclose control devices for an isolating switch with three switching positions comprising a closed position, an open position and an earthing position, through which the isolating switch may be electrically or manually activated. The control devices comprise a main rotary shaft that will be coupled to the mobile contact of the isolating switch. This mobile shaft is rotated during switching operations, either by an electric motor or manually through a crank that is then coupled with a manual switching member connected in movement to the main shaft.
More precisely, these documents describe control devices for a three-position isolating switch, comprising two manual switching members, one which switches the isolating switch from its closed position to its open position or vice versa, and the other that switches the isolating switch from its open position to its earthing position or vice versa.
EP 1 271 588-A1 describes an isolating switch control in which a mechanism is integrated preventing some manual switching sequences of the isolating switch to satisfy the particular requirements of a user.
EP 1 271 589-A1 describes an isolating switch control also comprising a means of locking the rotary movement of the crank when the isolating switch reaches its open position from its closed position or from its earthing position.
Isolating switch control devices described in these two documents have disadvantages.
Firstly, these isolating switch control devices comprise an interlocking mechanism, for which the arrangement and the configuration can prevent some manual switching sequences of the isolating switch. For example, it is impossible to perform an earthing operation following a closing operation.
Furthermore, these isolating switch control devices comprise two separate openings into which the crank can be inserted to switch manually between the closed position and the open position, or between the open position and the earthing position. Each opening is provided with a coupling part that will mechanically connect the stop bolt to the control and a closing member to prevent the crank from being inserted into the opening when the switch is in a position preventing the corresponding operation. Each of these two openings is also provided with at least one bolt. It is difficult and expensive to duplicate these parts.
Furthermore, the interlocking mechanism of these isolating switch control devices is controlled by a secondary shaft that is driven by the main shaft through a bevel gear. However, there is a risk that the interlocking mechanism is in a position that does not correspond to the position of the main shaft, which can cause unwanted manual operations.
Consequently, there is a need for a mechanical control device for a switchgear with three switching positions without the disadvantages in control devices mentioned above.